The Core Leader, Dr. Hilenski, has demonstrated capabilities in fluorescence microscopy and immunocytochemistry of cultured cells (1-10) and immunohistochemistry of tissues (11, 12). The Microscopy and Histology Core was established in 2000, with Dr. Hilenski appointed as director. Since this time, the core facility has supported studies on (a) detection of ROS production by cytochemical fluorescence methods within arteries both in animal (13-16) and in human vascular disease (17);(b) the localization of signaling molecules in angiotensin II (5, 8, 18, 19), redox-sensitive (7) and angiogenic (7, 9, 10, 20) pathways in vascular cells and tissues;(c) localization of NADPH oxidase components in vascular cells and tissues (6, 21, 22);(d) characterization of transgenic mouse models for hypertension (23) and hypertrophy (24);(e) morphometric measurements of vascular hypertrophy (25, 26) and atherosclerotic lesion size (24, 27);(f) immunostaining of ischemic and nonischemic tissues in mouse models of impaired neovascularization (28);(g) immunohistochemical staining of cell-specific (17, 29), inflammatory (30, 31) and atherosclerotic markers in lesions and vascular wall remodeling (29, 31-33);(h) localization of fluorescent eNOS mRNA and actin isoforms in endothelial cells (34);(i) immunohistochemical staining of bone morphogenic protein 4 (BMP4) and secreted BMP antagonists in cultured bovine endothelial cells and in mouse and human blood vessels exposed to unstable flow conditions (35);and (j) immunostaining of inflammatory cells in aortas in mouse models of hypertension (26).